This invention relates to the maintenance and repair of pipelines that carry or supply fluid and which are subsurface, either underground or sub marine. Such pipelines extend horizontally and involve lateral connections as well as vertical standpipe and/or connections, and all of which require additions and deletion, maintenance and repair. Therefore, pipe line servicing requires cutting into and the replacement of sections of such pipelines which carry liquids or gas, many of which are dangerous; as such fluids may be toxic or volitile, or even in the case of water which may cause unwanted flooding. Prior art methods of pipeline servicing have involved the use of various types of plugs to close the open ends of pipelines during service. But the plug closures heretofore employed have not been alltogether reliable as they have been subject to displacement under fluid pressure build-up in the pipeline, and unexpected surges. It is therefore a general object of this invention to provide an anchor-seal that is adapted to be securely placed within a pipeline in a predetermined position before any hazardous work commences. With the present invention, a vented plug is releasably anchored and sealed within the pipeline by insertion to a placement which isolates fluids that remain behind said seal.
Heretofore, pipeline workman have devised ways to plug the open ends of pipelines, but which have been subject to failure. For example, filling the end of the pipe with rags and placing a cake of mud thereover as a seal. Or for example, inflating or expanding a plug within the end of the pipe for frictional sealed engagement therein. Invariably, such methods of pipeline closure are subject to failure, since such plugs are displaceable by relatively low differential pressure, in which case they ar either blown out of or down the pipe. Since pipeline servicing involves spark generating work proceedures such as grinding and cutting or welding with torches, a hazard exists when such a plug is moved or displaced. It is therefore an object of this invention to provide an effective anchor separate from a seal that plugs the pipeline opening, and an anchor and seal that are simultaneously operable through releasable means. In carrying out this invention, a pressure actuating means controllably sets and releases the anchor and seal. It is also an object to provide for remote control of the releasably set operation of this device. And it is still another object to remotely vent the pipeline behind the set device, whereby discharge of fluid under pressure can be remote form the working area. With the present invention the working environment is made safe, despite fluid discharge and changing pressure conditions that may occur in the pipeline during the servicing period.